U.S. patent number 7,014,584 [Application Number 10/329,499] was granted by the patent office on 2006-03-21 for top pull type front derailleur.
This patent grant is currently assigned to Shimano Inc.. Invention is credited to Kanji Kirimoto, Yoshiaki Nanko.
United States Patent |
7,014,584 |
Nanko , et al. |
March 21, 2006 |
Top pull type front derailleur
Abstract
A top pull type front derailleur is designed to move or shift a
chain between two or more sprockets for changing gears. The front
derailleur basically has a bicycle frame clamping band, a linkage
assembly and a chain guide. The linkage assembly includes a cable
connection point and is arranged between the bicycle frame clamping
band and the chain guide to move the chain guide laterally towards
and away from the clamping band. The clamping band has a top pull
cable guide surface that is configured and arranged relative to the
clamping band to guide a cable from vertically above the clamping
band to the cable connection point when the front bicycle
derailleur is operatively mounted to a bicycle frame. Preferably,
the top pull cable guide surface is formed on a peripheral surface
of a roller that is rotatably mounted on the clamping band.
Inventors: |
Nanko; Yoshiaki (Sakai,
JP), Kirimoto; Kanji (Kaizuka, JP) |
Assignee: |
Shimano Inc. (Osaka,
JP)
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Family
ID: |
32469033 |
Appl.
No.: |
10/329,499 |
Filed: |
December 27, 2002 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20040127314 A1 |
Jul 1, 2004 |
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Current U.S.
Class: |
474/80;
474/82 |
Current CPC
Class: |
B62M
9/1342 (20130101); B62M 9/135 (20130101); B62M
9/137 (20130101) |
Current International
Class: |
F16H
61/04 (20060101) |
Field of
Search: |
;474/78-82
;74/502.4,502.6 ;411/302 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 788 485 |
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Jul 2000 |
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FR |
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52-162644 |
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Dec 1977 |
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JP |
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60-7994 |
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Mar 1985 |
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JP |
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Other References
Cycle Sports, Aug. 1992, Japan. cited by other .
Bible, Nov. 1993, Japan. cited by other .
Cycle Sports, Jun. 1995, japan. cited by other.
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Primary Examiner: Charles; Marcus
Attorney, Agent or Firm: Shinjyu Global IP Counselors,
LLP
Claims
What is claimed is:
1. A top pull front derailleur comprising: a bicycle frame clamping
portion including a frame mounting portion, a top pull cable guide
surface and a fixing member; first and second linkage members
including inner pivot ends and outer pivot ends, the inner pivot
ends being pivotally coupled to the fixing member, respectively,
one of the first and second linkage members further including a
cable connection point disposed laterally from a center plane of a
bicycle frame; and a chain guide including pivots pivotally coupled
to the outer pivot ends of the first and second linkage members,
respectively, to move the chain guide laterally towards and away
from the bicycle frame clamping portion, the pivots of the chain
guide being configured and arranged to remain above the frame
mounting portion during and after movement of the chain guide
laterally towards and away from the bicycle frame clamping portion,
the top pull cable guide surface being configured and arranged
relative to the bicycle frame clamping portion to guide a
derailleur cable from vertically above the bicycle frame clamping
portion to the cable connection point, the top pull cable guide
surface being further configured and arranged laterally from the
center plane such that the cable connection point and the top pull
cable guide are on a same side of the center plane.
2. The top pull front derailleur according to claim 1, wherein the
top pull cable guide surface is formed on a peripheral surface of a
roller that is rotatably mounted on the bicycle frame clamping
portion to rotate about a rotation axis.
3. The top pull front derailleur according to claim 2, wherein a
section of the top pull cable guide surface is arranged to be
substantially adjacent a center plane of a bicycle frame.
4. The top pull front derailleur according to claim 2, wherein the
top pull cable guide surface and the cable connection point are
arranged such that the top pull cable guide surface is disposed
laterally between the cable connection point and a center plane of
a bicycle frame.
5. The top pull front derailleur according to claim 2, wherein the
rotation axis of the roller and the cable connection point are
substantially aligned along a plane that is parallel to a center
plane of a bicycle frame.
6. The top pull front derailleur according to claim 2, wherein the
first linkage member includes a link portion with a longitudinal
axis and an extension portion with the cable connection point
formed thereon, the extension portion extending substantially
perpendicular to the longitudinal axis of the link portion.
7. The top pull front derailleur according to claim 2, wherein the
top pull cable guide surface, the first linkage member and the
cable connection point are arranged relative to each other such
that the derailleur cable is pulled in a direction from a first
distal position to a second proximal position that is closer to the
chain guide than the first distal position.
8. The top pull front derailleur according to claim 2, wherein the
top pull cable guide surface, the first linkage member and the
cable connection point are arranged relative to each other when the
chain guide is located in a middle gear position that is located
laterally farthest from the bicycle frame clamping portion such
that a cable section of the derailleur cable that extends between
the first linkage member and the top pull cable guide surface
extends substantially perpendicular to a line extending between a
pivot axis where the first linkage member is coupled to the fixing
member and to a point where the cable section of the derailleur
cable leaves the first linkage member.
9. The top pull front derailleur according to claim 1, wherein a
section of the top pull cable guide surface is arranged to be
substantially adjacent a center plane of a bicycle frame.
10. The top pull front derailleur according to claim 1, wherein the
top pull cable guide surface and the cable connection point are
arranged such that the top pull cable guide surface is at least
partially disposed laterally between the cable connection point and
a center plane of a bicycle frame.
11. The top pull front derailleur according to claim 1, wherein the
top pull cable guide surface and the cable connection point are
disposed laterally on a first lateral side of a pivot axis where
the inner pivot end of the first linkage member is pivotally
coupled, and the chain guide is located on a second lateral side of
the first pivot.
12. The top pull front derailleur according to claim 1, wherein the
first linkage member includes a link portion with a longitudinal
axis and an extension portion with the cable connection point
formed thereon, the extension portion extending substantially
perpendicular to the longitudinal axis of the link portion.
13. The top pull front derailleur according to claim 1, wherein the
top pull cable guide surface, the first linkage member and the
cable connection point are arranged relative to each other such
that the derailleur cable is pulled in a direction from a first
distal position to a second proximal position that is closer to the
chain guide than the first distal position.
14. The top pull front derailleur according to claim 1, wherein the
top pull cable guide surface, the first linkage member and the
cable connection point are arranged relative to each other when the
chain guide is located in a middle gear position that is located
laterally farthest from the bicycle frame clamping portion such
that a cable section of the derailleur cable that extends between
the first linkage member and the top pull cable guide surface
extends substantially perpendicular to a line extending between a
pivot axis where the first linkage member is coupled to the fixing
member and to a point where the cable section of the derailleur
cable leaves the first linkage member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a front derailleur for a
bicycle. More specifically, the present invention relates to a
front derailleur for a bicycle.
2. Background Information
Bicycling is becoming an increasingly more popular form of
recreation as well as a means of transportation. Moreover,
bicycling has become a very popular competitive sport for both
amateurs and professionals. Whether the bicycle is used for
recreation, transportation or competition, the bicycle industry is
constantly improving the various components of the bicycle. The
various components of the bicycle are usually mounted to the
bicycle frame. Some components of the bicycle that have been
extensively redesigned are the bicycle derailleurs.
One component that is mounted to the bicycle frame is the front
derailleur. Generally speaking, the front derailleur is typically
secured to the seat tube of the bicycle frame. The front derailleur
basically includes a fixed member nonmovably secured to the seat
tube of the bicycle frame, and a movable section supported to be
movable relative to the fixed member. The movable section supports
a chain guide having a pair of vertical surfaces for contacting a
chain.
When the derailleur is mounted to the seat tube, the shift or
derailleur cable can be mounted to run longitudinally along the
sear tube. Typically, a braze-on connection is permanently fastened
to the seat tube at a predetermined location. Depending upon the
location of the braze-on connection, the angle at which the shift
cable is connected to the derailleur may change such that a large
pulling force is required to shift the derailleur. In other words,
if the angle of the cable relative to the derailleur becomes too
small, the derailleur may become difficult to shift. Therefore, a
front derailleur may not operate very well on frames with very
small seat tubes.
In view of the above, it will be apparent to those skilled in the
art from this disclosure that there exists a need for a bicycle
with an improved front derailleur assembly. This invention
addresses this need in the art as well as other needs, which will
become apparent to those skilled in the art from this
disclosure.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a front
derailleur that can be mounted on a wide range of frame sizes.
Another object is to provide a front derailleur that is relatively
easy to produce at a relatively inexpensive price.
Yet another object is to provide a front derailleur that is very
easy to operate.
The foregoing objects can basically be attained by providing a
derailleur for a bicycle is provided that is easy to operate. The
front derailleur basically has a bicycle frame clamping portion, a
linkage assembly with first and second linkage members, and a chain
guide. The bicycle frame clamping portion includes a frame mounting
portion, a top pull cable guide surface and a fixing member. The
first and second linkage members including inner pivot ends and
outer pivot ends, with the inner pivot ends being pivotally coupled
to the first and second pivots of the fixing member, respectively,
one of the first and second linkage members further including a
cable connection point. The chain guide includes pivots that are
pivotally coupled to the outer pivot ends of the first and second
linkage members, respectively, to move the chain guide laterally
towards and away from the bicycle frame clamping portion. The top
pull cable guide surface is configured and arranged relative to the
bicycle frame clamping portion to guide a derailleur cable from
vertically above the bicycle frame clamping portion to the cable
connection point.
These and other objects, features, aspects and advantages of the
present invention will become apparent to those skilled in the art
from the following detailed description, which, taken in
conjunction with the annexed drawings, discloses preferred
embodiments of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the attached drawings which form a part of this
original disclosure:
FIG. 1 is a side elevational view of a bicycle with a front
derailleur in accordance with the present invention;
FIG. 2 is a perspective view of a front shifter or shift operating
device that operates the front derailleur illustrated in FIG.
1;
FIG. 3 is a rear elevational view of the front derailleur in a low
gear position in accordance with a first embodiment of the present
invention;
FIG. 4 is a rear elevational view of the front derailleur
illustrated in FIG. 3 with the front derailleur in a middle gear
position in accordance with the first embodiment of the present
invention;
FIG. 5 is a rear elevational view of the front derailleur
illustrated in FIGS. 2 and 4 with the front derailleur in a top
gear position in accordance with the first embodiment of the
present invention;
FIG. 6 is a side elevational view of the front derailleur
illustrated in FIGS. 3, 4 and 5 with the front derailleur in a top
gear position in accordance with the first embodiment of the
present invention;
FIG. 7 is a top plan view of the front derailleur illustrated in
FIGS. 3-6 with the derailleur in the top gear position in
accordance with the first embodiment of the present invention;
FIG. 8 is a rear elevational view of a front derailleur in
accordance with a second embodiment of the present invention with
the front derailleur in a low gear position;
FIG. 9 is a rear elevational view of the front derailleur
illustrated in FIG. 8 with the front derailleur in a middle gear
position in accordance with the second embodiment of the present
invention;
FIG. 10 is a rear elevational view of the front derailleur
illustrated in FIGS. 8 and 9 with the front derailleur in a top
gear position in accordance with the second embodiment of the
present invention;
FIG. 11 is a side elevational view of the front derailleur
illustrated in FIGS. 8-10 with the front derailleur in a top gear
position in accordance with the first embodiment of the present
invention; and
FIG. 12 is a top plan view of the front derailleur illustrated in
FIGS. 9-11 with the derailleur in the middle gear position in
accordance with the second embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Selected embodiments of the present invention will now be explained
with reference to the drawings. It will be apparent to those
skilled in the art from this disclosure that the following
descriptions of the embodiments of the present invention are
provided for illustration only and not for the purpose of limiting
the invention as defined by the appended claims and their
equivalents.
Referring initially to FIGS. 1-3, a bicycle 10 is illustrated with
a front derailleur 12 fixedly coupled to its seat tube or tube 14
of the bicycle frame. The front derailleur 12 is operated in a
conventional manner by a shifting unit 16 via a shift or derailleur
cable 18 to move a chain 20 between three front sprockets 22a, 22b
and 22c of the drive train The shifting unit 16 is mounted on the
handlebar 24 as seen in FIG. 2.
Bicycles and their various components are well known in the art,
and thus, bicycle 10 and its various components will not be
discussed or illustrated in detail herein, except for the
components that relate to the present invention. In other words,
only the front derailleur 12 and the components that relate thereto
will be discussed and/or illustrated herein. As used herein, the
terms "forward, rearward, upward, above, downward, below and
transverse" refer to those directions of a bicycle in its normal
riding position, to which the front derailleur 12 is attached.
Accordingly, these terms, as utilized to describe the front
derailleur 12 in the claims, should be interpreted relative to
bicycle 10 in its normal riding position.
Basically, as seen in FIGS. 3-7, the front derailleur 12 includes a
bicycle frame clamping band or tubular clamping portion 30, a chain
guide 31, a linkage assembly 32 and a biasing member 33. The
linkage assembly 32 is coupled between the clamping band 30 and the
chain guide 31 to move the chain guide 31 laterally-towards and
away from the clamping band. The linkage assembly 32 is preferably
designed such that the biasing member (torsion spring) 33 normally
biases the chain guide 31 in a transverse direction towards the
frame of the bicycle 10.
As best seen in FIGS. 3-6, the clamping band 30 is located above
the chain guide 31 such that the chain guide 31 moves from a
retracted (low gear) position to an extended (high gear) position
when the cable 18 is pulled as indicated by arrow A. The clamping
band 30 includes a frame mounting portion 34, a top pull cable
guide roller 35 and a fixing portion or member 36 that attaches the
linkage assembly 32 to the frame mounting portion 34 of the
clamping band 30. The clamping band 30 is preferably clamped
directly to the seat tube 14 by the frame mounting portion 34.
As best seen in FIG. 7, the frame mounting portion 34 of the
clamping band 30 basically includes a first C-shaped clamping
portion 34a, a second C-shaped clamping portion 34b, a pivot pin 40
and a fastener 42. When the first and second clamping portions 34a
and 34b are coupled together, a center frame mounting axis C if
formed by the curved inner mounting surfaces of the first and
second clamping portions 34a and 34b. This center frame mounting
axis C corresponds to the center axis of the seat tube 14. The
first and second clamping portions 34a and 34b are constructed of a
rigid material to secure the front derailleur 12 to the seat tube
14 of the bicycle 10. Preferably, the clamping portions 34a and 34b
are constructed of metal. Of course, the clamping portions 34a and
34b could be constructed of other materials such as a hard rigid
plastic material. In the illustrated embodiment, the clamping
portions 34a and 34b are constructed by utilizing other
conventional manufacturing techniques such as casting and/or
machining. Of course, the clamping portions 34a and 34b can also be
constructed of sheet metal that is bent to the desired shape.
The first ends of the clamping portions 34a and 34b are pivotally
coupled together by the pivot pin 40, which extends in a
substantially vertical direction relative to bicycle 10. The other
ends of the clamping portions 34a and 34b are releasably connected
together via the fastener 42. The fastener 42 is preferably a screw
or bolt that is threaded into a threaded hole of the first clamping
portion 34a. Of course, the fastener 42 can be utilized in
conjunction with a nut, or the like.
The clamping portion 34a includes the fixing member 36 for coupling
the linkage assembly 32 thereto. The fixing member 36 has a first
pivot hole 50 for receiving a first pivot pin 51 therein to couple
another portion of the linkage assembly 32 thereto. Preferably, the
pivot pin 51 is a rivet or other suitable fastener. The fixing
member 36 also has a pair of substantially parallel mounting
flanges 52 and 53 that are horizontally spaced apart. The mounting
flanges 52 and 53 each have a pivot hole that receives a second
pivot pin 54 for mounting a portion of the linkage assembly 32
thereto, as explained below. Preferably, the pivot pin 54 is a
rivet or other suitable fastener. As explained below in more
detail, the fixing member 36 with the first pivot hole 50 forms one
of the links (third link) of the linkage assembly 32. Thus, fixing
member 36 includes portions (i.e., the third link with the first
and second pivots) of the linkage assembly 32. In other words, the
portion of the fixing member 36 that includes the pivot pins 51 and
54 forms a non-movable third link of the linkage assembly 32.
The clamping portion 34a has a pair of vertically extending flanges
55 that rotatably mounts the top pull cable guide roller 35 to the
clamping band 30 in a fixed position. Thus, the cable 18 is always
coupled to the front derailleur 12 in the same way. In other words,
the dimensions of the seat tube 14 does not change the orientation
of the cable 18 where it is attached to the front derailleur 12.
The top pull cable guide roller 35 is rotatably coupled to the
flanges 55 by a pivot pin 56 that has a rotation axis R. The top
pull cable guide roller 35 has a peripheral cable receiving groove
35a that guides the cable 18. The radially innermost area of the
cable receiving groove 35a forms a top pull cable guide surface S
that configured and arranged relative to the clamping band 30 to
guide the cable 18 from vertically above the clamping band 30 to a
cable connection point P, when the front bicycle derailleur 14 is
operatively mounted to a bicycle frame. Thus, the top pull cable
guide surface S is formed on the inner peripheral surface of the
roller 35. It will be apparent from this disclosure that instead of
using the roller 35, a non-rotating member can be used, if needed
and/or desired. The top pull cable guide surface S and the cable
connection point P are arranged such that the cable 18 extends
substantially perpendicular to the center frame mounting axis C of
the frame mounting portion 34 of the clamping band 30. Preferably,
a section of the top pull cable guide surface S is arranged to be
substantially adjacent or aligned with the center frame mounting
axis C of the frame mounting portion 34 of the clamping band 30.
The top pull cable guide surface S and the cable connection point P
are further arranged in this embodiment such that the top pull
cable guide surface S is at least partially disposed laterally
between the cable connection point P and the center frame mounting
axis C of the frame mounting portion 34 of the clamping band 30.
The top pull cable guide surface S is disposed laterally on one
lateral side of the first pivot pin 51, and the chain guide 31 is
located on a second lateral side of the first pivot pin 51. The top
pull cable guide surface S, the pivot axis of the pivot pin 54 and
the cable connection point P are substantially aligned laterally to
form a line L.sub.1 that extends perpendicularly to a center frame
mounting axis C of the frame mounting portion 34 of the clamping
band 30.
The chain guide 31 is preferably constructed of a hard rigid
material. For example, the chain guide 31 is preferably constructed
of a metal material such as a rigid sheet metal that is bent to the
desired shape. The chain guide 31 has a chain receiving slot that
is formed by a pair of vertical shift plates 31a and 31b. The
vertical shift plates 31a and 31b are adapted to engage the chain
20 and thus move the chain 20 in a direction substantially
transverse to the bicycle 10. The shift plates 31a and 31b are
connected together by a pair of plates 31c and 31d. The upper plate
31c is integrally formed between the shift plates 31a and 31b. The
lower plate 31d has one end that is integrally formed with the
outer shift plate 31b and the other end that is attached to the
inner shift plate 31a via a fastener 60, such as a screw or
rivet.
The chain guide 31 also has a pair of first mounting flanges 61
(only one shown) extending outwardly from the inner shift plate 31a
for pivotally coupling a first link of the linkage assembly 32
thereto by a third pivot pin 62. The chain guide 31 also has a pair
of second mounting flanges 63 extending in a substantially vertical
direction from the plate 31c for pivotally coupling a second link
of the linkage assembly 32 thereto by a fourth pivot pin 64. As
explained below in more detail, the portion of the chain guide 31
with the mounting flanges 61 and 63 forms one of the links (fourth
link) of the linkage assembly 32. Thus, the chain guide 31 includes
portions (i.e., the fourth link with the third and fourth pivots)
of the linkage assembly 32. In other words, the portion of the
chain guide 31 that includes the pivot pins 62 and 64 forms a
fourth link of the linkage assembly 32.
As apparent from the discussion above, the linkage assembly 32 is
preferably a four-bar linkage that is formed by a first link or
linkage member 71 and a second link or linkage member 72 extending
between the fixing member 36 and the chain guide 31. As mentioned
above, the portion of the fixing member 36 that includes the pivot
pins 51 and 54 forms the third link, while the portion of the chain
guide 31 that includes the pivot pins 62 and 64 forms the fourth
link. The first and second links 71 and 72 have their inner pivot
ends pivotally coupled to the first and second pivots of the fixing
member 36 via the pivot pins 51 and 54 and their outer pivot ends
pivotally coupled to the third and fourth pivots of the chain guide
31, respectively, via the pivot pins 62 and 64. In this embodiment,
the third and fourth pivots are located below the frame mounting
portion 34.
When the linkage assembly 32 holds the chain guide 31 in its
extended position, the chain guide 31 is located over the outermost
sprocket 22c, i.e., the furthest sprocket from the seat tube 14.
These movements of the chain guide 31 and the linkage assembly 32
are controlled by the shifting unit 16. Specifically, when the
rider operates one of the levers of the shifting unit 16 to pull
the shift cable 18 against the urging force of the biasing member
33, then the chain guide 31 is moved from one of its retracted
position to its one of extended position via the linkage assembly
32. When the rider operates one of the levers of the shifting unit
16 to release the shift cable 18, then the chain guide 31 is moved
from its one of extended position to its one of retracted position
via the linkage assembly 32 by the urging force of the biasing
member 33.
The first link 71 has a pair of pivot points formed by the pivot
pins 51 and 62 that lie on a longitudinal line which is
substantially parallel to a longitudinal line that passes through
the pivot points formed by the pivot pins 54 and 64 of the second
link 72. Similarly, the pivot points of the pivot pins 51 and 54 of
each first end of the first and second links 71 and 72 lie on a
line which is substantially parallel to a line that passes through
the pivot points of the pivot pins 62 and 64 of the other or second
ends of the first and second links 71 and 72.
The first link 71 is operatively coupled to the shifting unit 16
via the shift cable 18 for moving the chain guide 31 between the
first, second and third gear positions. More specifically, the
first link 71 is a L-shaped member that is pivotally mounted on the
pivot pin 51 extending outwardly from the first C-shaped clamping
portion 34a. The first link 71 has two mounting holes that receive
the pivot pins 51 and 62 for the linkage assembly 32.
The first link 71 includes a link portion 71a and an extension
portion 71b. The link portion 71a has the first and third pivots.
The extension portion 71b has the cable connection point P formed
thereon. The extension portion 71b of the first link 71 has a cable
attachment member or screw 73 coupled thereto to form a cable
attachment point P at its free end. The cable attachment member 73
is a wire clamp for attaching the inner wire of cable 18
thereto.
The first pivot axis of pivot pin 51 and the cable connection point
P are arranged along a line L.sub.2 that intersects with the line
L.sub.1 at the cable connection point P. In the bottom gear
position (FIG. 3), the line L.sub.2 intersects with the line
L.sub.1 at an acute angle that is close to seventy five degrees. In
the middle gear position (FIG. 4), the line L.sub.2 intersects with
the line L.sub.1 at an obtuse angle that is close to one hundred
degrees (substantially ninety). In the top gear position (FIG. 5),
the line L.sub.2 intersects with the line L.sub.1 at an obtuse
angle that is close to one hundred twenty-five degrees. Thus, the
top pull cable guide surface S, the first pivot axis of pivot pin
51 and the cable connection point P are arranged relative to each
other when the chain guide 31 is located in a middle position (FIG.
4) such that a section of the cable 18 that extends between the
first link 71 and the top pull cable guide surface S extends
substantially perpendicular to the line L.sub.2 extending from the
first pivot axis of the pivot pin 51 to cable connection point P
where the section of the cable 18 leaves the extension portion
71b.
The biasing member 33 is preferably a torsion spring having its
coiled portion positioned around the pivot pin 51. The biasing
member 33 urges the first and second links 71 and 72 in a direction
such that the chain guide 31 is urged to a low gear position that
is located laterally adjacent to the clamping band 30. The biasing
member 33 has a first end 33a engaging a side of the first link 71,
and a second end 33b engaging a portion on the fixing member 36 of
the clamping band 30 for normally biasing the chain guide 31 from
its extended position to its retracted position. In other words,
biasing member or torsion spring 33 is normally placed under
tension to urge the cable guide 32 from its extended position to
its retracted position. Of course, movement of the chain guide 31
is controlled by the shifting unit 16 moving cable 18 in a
relatively conventional manner.
Second Embodiment
Referring now to FIGS. 8-12, a front derailleur 12' in accordance
with a second embodiment will now be explained. The front
derailleur 12' is installed on the bicycle 10 such that the front
derailleur 12' is operated by the front shifter 16 via the cable
18. Basically, the front derailleur 12' includes a bicycle frame
clamping band or tubular clamping member 30', a chain guide 31', a
linkage assembly 32' and a biasing member 33'. The linkage assembly
32' is coupled between the clamping band 30' and the chain guide
31' to move the chain guide 31' laterally towards and away from the
clamping band. The linkage assembly 32' is preferably designed such
that the biasing member (torsion spring) 33' normally biases the
chain guide 31' in a transverse direction towards the frame of the
bicycle 10.
The clamping band 30' is located below the chain guide 31' such
that the chain guide 31' moves from a retracted (low gear) position
to an extended (high gear) position when the cable 18 is pulled as
indicated by arrow A'. The clamping band 30' includes a frame
mounting portion 34', a top pull cable guide roller 35' and a
fixing portion or member 36' that attaches the linkage assembly 32'
to the clamping band 30'. The clamping band 30' is preferably
clamped directly to the seat tube 14.
The frame mounting portion 34' of the clamping band 30' basically
includes a first C-shaped clamping portion 34a', a second C-shaped
clamping portion 34b', a pivot pin 40' and a fastener 42'. When the
first and second clamping portions 34a' and 34b' are coupled
together, a center frame mounting axis C' if formed by the curved
inner mounting surfaces of the first and second clamping portions
34a' and 34b'. This center frame mounting axis C' corresponds to
the center axis of the seat tube 14. The first and second clamping
portions 34a' and 34b' are constructed of a rigid material to
secure the front derailleur 12' to the seat tube 14 of the bicycle
10. Preferably, the clamping portions 34a' and 34b' are constructed
of metal. Of course, the clamping portions 34a' and 34b' could be
constructed of other materials such as a hard rigid plastic
material. In the illustrated embodiment, the clamping portions 34a'
and 34b' are constructed by utilizing other conventional
manufacturing techniques such as casting and/or machining. Of
course, the clamping portions 34a' and 34b' can also be constructed
of sheet metal that is bent to the desired shape.
The first ends of the clamping portions 34a' and 34b' are pivotally
coupled together by the pivot pin 40', which extends in a
substantially vertical direction relative to bicycle 10. The other
ends of the clamping portions 34a' and 34b' are releasably
connected together via the fastener 42'. The fastener 42' is
preferably a screw or bolt that is threaded into a threaded hole of
the first clamping portion 34a'. Of course, the fastener 42' can be
utilized in conjunction with a nut, or the like.
The clamping portion 34a' includes the fixing member 36' for
coupling the linkage assembly 32' thereto. The fixing member 36'
has a first pivot hole 50' for receiving pivot pin 51' therein to
couple another portion of the linkage assembly 32' thereto.
Preferably, the pivot pin 51' is a rivet or other suitable
fastener. The clamping portion 34a' also has a pair of
substantially parallel mounting flanges 52' and 53' that are
horizontally spaced apart. The mounting flanges 52' and 53' each
have a pivot hole receives that a second pivot pin 54' for mounting
a portion of the linkage assembly 32' thereto, as explained below.
Preferably, the pivot pin 54' is a rivet or other suitable
fastener. As explained below in more detail, the fixing member 36'
with the first pivot hole 50' forms one of the links (third link)
of the linkage assembly 32'. Thus, the fixing member 36' includes
portions (i.e., the third link with the first and second pivots) of
the linkage assembly 32'. In other words, the portion of the fixing
member 36' that includes the pivot pins 51' and 54' forms a
non-movable third link of the linkage assembly 32'.
The clamping portion 34a' has a vertically extending flange 55'
that rotatably mounts the top pull cable guide roller 35' to the
clamping band 30' in a fixed position. Thus, the cable 18 is always
coupled to the front derailleur 12' in the same way. In other
words, the dimensions of the seat tube 14 does not change the
orientation of the cable 18 where it is attached to the front
derailleur 12'. The top pull cable guide roller 35' is rotatably
coupled to the flange 55' by a pivot pin 56' that has a rotation
axis R'.
The top pull cable guide roller 35' has a peripheral cable
receiving groove 35a' that guides the cable 18. The radially
innermost area of the cable receiving groove 35a' forms a top pull
cable guide surface S that configured and arranged relative to the
clamping band 30' to guide the cable 18 from vertically above the
clamping band 30' to a cable connection point P', when the front
bicycle derailleur 14' is operatively mounted to a bicycle frame.
Thus, the top pull cable guide surface S' is formed on a peripheral
surface of the roller 35'. It will be apparent from this disclosure
that instead of using the roller 35', a non-rotating member can be
used, if needed and/or desired.
In this embodiment, the first pivot pin 50' is arranged on the
opposite side of the center frame mounting axis C' of the clamping
band 30' from the top pull cable guide surface S' and the cable
connection point P'. Preferably, similar to the first embodiment, a
section of the top pull cable guide surface S' is arranged to be
substantially adjacent or aligned with the center frame mounting
axis C' of the frame mounting portion 34' of the clamping band 30'.
The top pull cable guide surface S' and the cable connection point
P' are further arranged in this embodiment such that the top pull
cable guide surface S' is at least partially disposed laterally
between the cable connection point P' and the center frame mounting
axis C' of the frame mounting portion 34' of the clamping band
30'.
The top pull cable guide surface S' and the cable connection point
P' are disposed laterally on a first lateral side of the first
pivot pin 51' of the frame mounting portion 34' of the clamping
band 30', and the chain guide 31' is located on a second lateral
side of the first pivot of the frame mounting portion 34' of the
clamping band 30'. The rotation axis R' of the roller 35' and the
cable connection point P' are substantially aligned along a plane
that is parallel to a center frame mounting axis C' of the frame
mounting portion 34' of the bicycle frame clamping band 30'.
The chain guide 31' is preferably constructed of a hard rigid
material. For example, the chain guide 31' is preferably
constructed of a metal material such as a rigid sheet metal that is
bent to the desired shape. The chain guide 31' has a chain
receiving slot that is formed by a pair of vertical shift plates
31a' and 31b'. The vertical shift plates 31a' and 31b' are adapted
to engage the chain 20 and thus move the chain 20 in a direction
substantially transverse to the bicycle 10. The shift plates 31a'
and 31b' are connected together by a pair of plates 31c' and 31d'.
The upper plate 31c' is integrally formed between the shift plates
31a' and 31b'. The lower plate 31d' has one end that is integrally
formed with the outer shift plate 31b' and the other end that is
attached to the inner shift plate 31a' via a fastener 60', such as
a screw or rivet.
The chain guide 31' also has a first mounting flange 61' extending
outwardly from the inner shift plate 31a' for pivotally coupling a
first link of the linkage assembly 32' thereto by a third pivot pin
62'. The chain guide 31' also has a pair of second mounting flanges
63' extending in a substantially vertical direction from the plate
31c' for pivotally coupling a second link of the linkage assembly
32' thereto by a fourth pivot pin 64'. As explained below in more
detail, the portion of the chain guide 31' with the mounting
flanges 61' and 63' forms one of the links (fourth link) of the
linkage assembly 32'. Thus, the chain guide 31' includes portions
(i.e., the fourth link with the third and fourth pivots) of the
linkage assembly 32'. In other words, the portion of the chain
guide 31' that includes the pivot pins 62' and 64' forms a fourth
link of the linkage assembly 32'.
As apparent from the discussion above, the linkage assembly 32' is
preferably a four-bar linkage that is formed by a first link or
linkage member 71' and a second link or linkage member 72'
extending between the fixing member 36' and the chain guide 31'. As
mentioned above, the portion of fixing member 36' that includes the
pivot pins 51' and 54' forms the third link, while the portion of
the chain guide 31' that includes the pivot pins 62' and 64' forms
the fourth link. The first and second links 71' and 72' have their
inner pivot ends pivotally coupled to the first and second pivots
of the fixing member 36' via the pivot pins 51' and 54' and their
outer pivot ends pivotally coupled to the third and fourth pivots
of the chain guide 31', respectively, via the pivot pins 62' and
64'. In this embodiment, the third and fourth pivots are located
above the frame mounting portion 34'.
When the linkage assembly 32' holds the chain guide 31' in its
extended position, the chain guide 31' is located over the
outermost sprocket 22c, i.e., the furthest sprocket from the seat
tube 14. These movements of the chain guide 31' and the linkage
assembly 32' are controlled by the shifting unit 16. Specifically,
when the rider operates one of the levers of the shifting unit 16
to pull the shift cable 18 against the urging force of the biasing
member 33', then the chain guide 31' is moved from one of its
retracted position to one of its extended position via the linkage
assembly 32'. When the rider operates one of the levers of the
shifting unit 16 to release the shift cable 18, then the chain
guide 31' is moved from one of its extended position to one of its
retracted position via the linkage assembly 32' by the urging force
of the biasing member 33'.
The first link 71' has a pair of pivot points formed by the pivot
pins 51' and 62' that lie on a longitudinal line which is
substantially parallel to a longitudinal line that passes through
the pivot points formed by the pivot pins 54' and 64' of the second
link 72'. Similarly, the pivot points of the pivot pins 51' and 54'
of each first end of the first and second links 71' and 72' lie on
a line which is substantially parallel to a line that passes
through the pivot points of the pivot pins 62' and 64' of the other
or second ends of the first and second links 71' and 72'.
The first link 71' is operatively coupled to the shifting unit 16
via the shift cable 18 for moving the chain guide 31' between the
first, second and third gear positions. More specifically, the
first link 71' is a L-shaped member that is pivotally mounted on
the pivot pin 51' extending outwardly from the first C-shaped
clamping portion 34a'. The first link 71' has two mounting holes
that receive the pivot pins 51' and 62' for the linkage assembly
32'.
The first link 71' includes a link portion 71a' and an extension
portion 71b'. The link portion 71a' has the first and third pivots
with a longitudinal axis extending between the first and second
pivots and an extension portion 71b' with the cable connection
point formed thereon. The extension portion 71b' extends
substantially perpendicular to the longitudinal axis of the link
portion 71a'. The extension portion 71b' has the cable connection
point P' formed thereon.
The extension portion 71b' of the first link 71' has a cable
attachment member or screw 73' coupled thereto to form a cable
attachment point P' at its free end. The cable attachment member
73' is a wire clamp for attaching the inner wire of cable 18
thereto. The top pull cable guide surface S', the first pivot axis
of pivot pin 51' and the cable connection point P' are arranged
relative to each other when the chain guide 31' is located in a
middle gear position (FIG. 9) such that a section of the cable 18
that extends between the first link 71' and the top pull cable
guide surface S' extends substantially perpendicular to a line
L.sub.3 extending from the first pivot axis of the pivot pin 51' to
a point P'' where the section of the cable 18 leaves the extension
portion 71b'. The first pivot axis of pivot pin 51' and the point
P'' are arranged along that line L.sub.3 that intersects with a
line L.sub.4 formed by a section of the cable 18. In the bottom
gear position (FIG. 8), the line L.sub.3 intersects with the line
L.sub.4 at an acute angle that is close to sixty degrees. In the
middle gear position (FIG. 9), the line L.sub.3 intersects with the
line L.sub.4 at an acute angle that is close to one eighty degrees
(substantially ninety degrees). In the top gear position (FIG. 10),
the line L.sub.3 intersects with the line L.sub.4 at an obtuse
angle that is close to one hundred twenty degrees. Thus, the top
pull cable guide surface S', the first pivot axis of pivot pin 51'
and the point P'' are arranged relative to each other when the
chain guide 31 is located in a middle position (FIG. 9) such that a
section (line L.sub.4) of the cable 18 that extends between the
first link 71' and the top pull cable guide surface S' extends
substantially perpendicular to the line L.sub.3 extending from the
first pivot axis of the pivot pin 51 to the point P'' where the
section of the cable 18 leaves the extension portion 71b'.
The biasing member 33' is preferably a torsion spring having its
coiled portion positioned around pivot pin 51' therein. The biasing
member 33' urges the first and second links 71' and 72' in a
direction such that the chain guide 31' is urged to a low gear
position that is located laterally adjacent to the clamping band
30'. The biasing member 33' has a first end 33a' engaging a side of
the first link 71', and a second end 33b' engaging a portion on the
fixing member 36' of the clamping band 30' for normally biasing the
chain guide 31' from its extended position to its retracted
position. In other words, biasing member or torsion spring 33' is
normally placed under tension to urge the cable guide 32' from its
extended position to its retracted position. Of course, movement of
the chain guide 31' is controlled by the shifting unit 16 moving
cable 18 in a relatively conventional manner.
The chain guide 31' also has a pair of adjustment screws 74' and
75' engage a portion of the linkage assembly 32' for controlling
the range of movement of the chain guide 31' in a conventional
manner. In other words, by individually adjusting the axial
extension of adjustment screws 74' and 75', the retracted (low
gear) position and the extended (high or top gear) position of the
chain guide 31' are adjusted independently of each other. Since
this is a relatively conventional adjustment mechanism that is well
known in the prior art, this adjustment mechanism will not be
discussed or illustrated in detail herein.
As used herein, the following directional terms "forward, rearward,
above, downward, vertical, horizontal, below and transverse" as
well as any other similar directional terms refer to those
directions of a bicycle equipped with the present invention.
Accordingly, these terms, as utilized to describe the present
invention should be interpreted relative to a bicycle equipped with
the present invention.
The terms of degree such as "substantially", "about" and
"approximately" as used herein mean a reasonable amount of
deviation of the modified term such that the end result is not
significantly changed. For example, these terms can be construed as
including a deviation of at least .+-.5% of the modified term if
this deviation would not negate the meaning of the word it
modifies.
While only selected embodiments have been chosen to illustrate the
present invention, it will be apparent to those skilled in the art
from this disclosure that various changes and modifications can be
made herein without departing from the scope of the invention as
defined in the appended claims. Furthermore, the foregoing
descriptions of the embodiments according to the present invention
are provided for illustration only, and not for the purpose of
limiting the invention as defined by the appended claims and their
equivalents. Thus, the scope of the invention is not limited to the
disclosed embodiments.
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